image quality, artifacts and hazards in imaging

Image Quality, Artifacts and Hazards in Imaging

Laura Gruber, MBA, RT(R), RDMS, RVT

Sr. Director

Medical Imaging

Case 1

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• What is the image quality issue in this picture?

Case Courtesy of Judy Le, R.T. (CT) (R)

Case 1

A.) Improper exposure/technique

B.) Detector burn-in or “ghosting” artifact

C.) Electromagnetic interference artifact (EMI)

D.) Artifact from a thermo-regulating blanket

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• What is the image quality issue in this picture?

Case Courtesy of Judy Le, R.T. (CT) (R)

Case 1

A.) Improper exposure/technique

B.) Detector burn-in or “ghosting” artifact

C.) Electromagnetic interference artifact (EMI)

D.) Artifact from a thermo-regulating blanket

Case 1

Key Concepts:

1.) Thermo-regulating blankets can cause“honey-comb” like artifacts if they are left inplace during xray. These artifacts do notobscure visibility of lines, however, they can bedistracting when evaluating bowel gas andpotential free air.

3.) When evaluating lines and lungs, thermo-regulating blankets are acceptable to leave in ifpatient condition prohibits removal. Ifevaluating pathology in the abdomen, artifactscaused by these blankets may affect diagnosticinterpretation.

5Case Courtesy of Judy Le, R.T. (CT) (R)

Case 2

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Case 2 What is the image quality issue in this picture?

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A.) Baby should be prone

B.) Immobilization board will create significant artifact

C.) Lead shield in the fluoroscopic field of view

D.) Using an image intensifier instead of flat panel fluoroscope

Case 2 What is the image quality issue in this picture?

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A.) Baby should be prone

B.) Immobilization board will create significant artifact

C.) Lead shield in the fluoroscopic field of view

D.) Using an image intensifier instead of flat panel fluoroscope

Case 2

Key Concepts:

1.) All modern fluoroscopes uses automatic brightness control(ABC) which means the machine adjusts the xray tube outputbased on how much attenuation it detects.

2.) A lead gonad shield in the fluoroscopy field of view will causethe fluoroscopy system to substantially increase radiation to thepatient AND compromise image quality.

3.) You should also not use lead shields in the field of view forother modalities that use automatic exposure control (ex.xray=phototiming, CT=dose modulation)

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Case 3

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Case 3 What is the image quality issue in this picture?

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A.) Improper exposure/technique

B.) Detector burn-in or “ghosting” artifact

C.) Electromagnetic interference artifact (EMI)

D.) Artifact from a positioning device

Case 3 What is the image quality issue in this picture?

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A.) Improper exposure/technique

B.) Detector burn-in or “ghosting” artifact

C.) Electromagnetic interference artifact (EMI)

D.) Artifact from a positioning device

Case 3

Key Concepts:

1.) Scoliosis exams are often performed with a series of 2or 3 images exposing the same detector in rapidsuccession.

2.) Though rare, the “burn-in” artifact can be seen in highmAs scoli exams, it is most often noted as a repeatedimage of the xray marker.

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Case 4

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Case 4

• What is the image quality issue in this picture?

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A.) Use of Lap Shield

B.) Room is not suitable for portable xray imaging

C.) Source-to-image distance is too short

D.) Portable xray tube should be under the table.

Case 4

• What is the image quality issue in this picture?

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A.) Use of Lap Shield

B.) Room is not suitable for portable xray imaging

C.) Source-to-image distance is too short

D.) Portable xray tube should be under the table.

Case 4• There is a ruler provided to help you determine the SID

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Case 4

Key Concepts:

1.) Portable xray protocols have defined SID’s, make sureyou try to approximate the correct distance so the dose isappropriate and the image quality is consistent.

2.) Use the ruler provided by the system and pick theappropriate protocol (27”, 40”, or 72”)

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Case 5

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Case 5 What is the image quality issue in this picture?

20Case Courtesy of Judy Le, R.T. (CT) (R)

A.) Improper exposure/technique

B.) Detector burn-in or “ghosting” artifact

C.) Electromagnetic interference artifact (EMI)

D.) Artifact from a positioning device

Case 5 What is the image quality issue in this picture?

21Case Courtesy of Judy Le, R.T. (CT) (R)

A.) Improper exposure/technique

B.) Detector burn-in or “ghosting” artifact

C.) Electromagnetic interference artifact (EMI)

D.) Artifact from a positioning device

Case 5

Key Concepts:

1.) Gel pillows are filled with a non-toxic waterbased gel that can provide the support needs ofmicro-preemie, preemie, and full-term infants

2.) Removal of gel pillows is highly recommendedfor any indication. Artifacts caused by gel pillowscan mimic pathology, such as free air, which canlead to misinterpretation by Radiologists.

3.) These gel positioning devices can lead toadditional x-rays to confirm artifact vs. pathology,resulting in increased radiation dose to the patient.

22Case Courtesy of Judy Le, R.T. (CT) (R)

Case 6

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Case 6 What is the image quality issue in this picture?

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A.) Chest chair is too large

B.) Baby should have arms down

C.) Holding is never acceptable in pediatric radiology

D.) Poor collimation

Case 6 What is the image quality issue in this picture?

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A.) Chest chair is too large

B.) Baby should have arms down

C.) Holding is never acceptable in pediatric radiology

D.) Poor collimation

Case 6

Key Concepts:

1.) Poor collimation is a source of poor image quality indigitally processed images.

2.) Differences in collimation introduces variability in thesource images and inconsistent results on processedimages.

2.) Collimation is also very effective at reducing our patient’sexposure (and it also reduces the exposure of anyone whois holding the child). Always collimate as much asreasonable!

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Case 7

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Case 7 What is the image quality issue in this picture?

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A.) Patient should be feet first first

B.) Patient is off iso-center

C.) Incorrect pediatric table insert in place

D.) Incorrect position on the table in the head-to-foot direction

Case 7 What is the image quality issue in this picture?

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A.) Patient should be feet first first

B.) Patient is off iso-center

C.) Incorrect pediatric table insert in place

D.) Incorrect position on the table in the head-to-foot direction

Case 7

• Automatic dose control requires good isocentering.

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Case 7

• Magnification = SID/SOD

Z-axis dose modulation

32Bushberg JT, et al. The Essential Physics of Medical Imaging, Wolters Kluwer, Philadelphia, 3rd Edition, 2012

Z-axis dose modulation

33Bushberg JT, et al. The Essential Physics of Medical Imaging, Wolters Kluwer, Philadelphia, 3rd Edition, 2012

Case 7

Key Concepts:

1.) Use your lasers to ensure very good centering of thepatient in the AP and RL directions.

2.) If you do notice you are off-isocenter, do not move yourplanning box to accommodate. Go back in the room andphysically reposition your table and acquire anothertopogram.

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Case 8

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Case 8 • What is the image quality issue in this picture?

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A.) Cosmetics containing glitter may lead totissue heating and discomfort during MRI

B.) Cosmetics containing glitter may lead toimaging artifacts in MRI

C.) Glitter tattoos can lead to bright spots inthe MRI image

D.) Both A and B

Case 8 • What is the image quality issue in this picture?

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A.) Cosmetics containing glitter may lead totissue heating and discomfort during MRI

B.) Cosmetics containing glitter may lead toimaging artifacts in MRI

C.) Glitter tattoos can lead to bright spots inthe MRI image

D.) Both A and B

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Case 8

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Case 8

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Case 8

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Case 9

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Case 9 What is the image quality issue in this picture?

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A.) Artifact due to patient motion

B.) Iterative reconstruction artifact

C.) Artifact due to contrast extravasation

D.) Ring artifact from detector failure

Case 9 What is the image quality issue in this picture?

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A.) Artifact due to patient motion

B.) Iterative reconstruction artifact

C.) Artifact due to contrast extravasation

D.) Ring artifact from detector failure

Case 9

Key Concepts:

1.) Contrast extravasation means that the scan quality willbe compromised and possibly non-diagnostic.

2.) Always check with an attending before continuing a scanwhere extravasation is suspected.

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Case 10

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Case 10 • What is the image quality issue in this picture?

47TG Sandridge, M Karastanovic, Radiologic Technology,

January/February 2015, Volume 86, Number 3

A.) Post-processing error

B.) Improper exposure/technique

C.) Electromagnetic interference artifact (EMI)

D.) Artifact from a positioning device

Case 10 • What is the image quality issue in this picture?

48TG Sandridge, M Karastanovic, Radiologic Technology,

January/February 2015, Volume 86, Number 3

A.) Post-processing error

B.) Improper exposure/technique

C.) Electromagnetic interference artifact (EMI)

D.) Artifact from a positioning device

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Case 10

Key Concepts:

1.) Some devices such as thisthermoregulation unit can interfereelectromagnetically with digitaldetectors.

2.) Electromagnetic interferenceartifacts often manifest as parallellines and can be eliminated if thesource of the interference can beremoved or turned off.

TG Sandridge, M Karastanovic, Radiologic Technology, January/February 2015, Volume 86, Number 3

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Case 10

TG Sandridge, M Karastanovic, Radiologic Technology, January/February 2015, Volume 86, Number 3

Thermoregulation Unit ON Thermoregulation Unit OFF

Case 11

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Case 11

• What is the hazard or compliance issue in this picture?

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Case 11

• Answer: Objects depressing the fluoroscopy foot-pedal!

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Case 11

Key Concepts:

1.) Always remember to practice safety with foot-pedal operateddevices. Keep them clear of equipment which can fall on to thepedal. Inhibit xrays if possible when the device is not in use.

2.) Become familiar with the “beam-on” alerts for your device,both visual and audio.

3.) Always wear your radiation badge in case of unexpectedexposures.

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Case 12

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Case 12

• What is the hazard or compliance issue in this picture?

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Case 12

• Answer: Someone ripped off the spacer cone!

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Case 12• Answer: The spacer cone is there to protect the patient’s skin.

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Case 12

Key Concepts:

1.) Never remove the spacer cone. This is in place to ensure theentrance skin dose to the patient is not too high and is regulatedby the State and Joint Commission.

2.) Remember that the xray radiation is highest directly at thetube output and decreases by 1/distance^2. Entrance skin doseis highest if anatomy is closer to tube output, so the spacer coneis there to reduce the likelihood of skin burns.

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Case 13

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Case 13

• What is the hazard or compliance issue in this picture?

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Case 13• Answer: This physician is entering the MRI room with his

pager and stethoscope!

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Case 13

Key Concepts:

1.) Most metal object MRI accidents occur because ofuntrained or absent-minded people entering with commonitems.

2.)As the most trained staff in the hospital, it’s our job toalways be vigilant with screening (even if it is a doctor orsupervisor who is entering the MRI room).

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Case 14

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Case 14

• What is the hazard or compliance issue in this picture?

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Case 14

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• Answer: A magnet quench may cause vaporized helium (awhite smoky substance) to fill the MRI scanner room.

Case 14

• MRI scanners are built with a exhaust for vaporized helium.

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Case 14

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• Example of vaporized helium exhaust from a quench. Failureof the exhaust system can lead to very high gas pressures inthe scanner room.

Case 14

Key Concepts:

1.) MRI system use superconducting technology that mustbe kept at cryogenic temperatures. Any disturbance to thiscryo system can lead to a quench.

2.) Quenches happen more often than you might think.Generally there is a audible loud bang, an immediate loss offield strength, and the room will fill with helium gas.

2.)Immediately evacuate all personnel from the area toavoid breathing in helium vapor and contact HTM.

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Case 15

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Case 15

• What is the hazard or compliance issue in this picture?

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Case 15

• Answer: Drinking cups in the Nuclear Medicine Hotlab!

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Case 15

Key Concepts:

1.) Eating, drinking, applying cosmetics or creams canintroduce radio-isotopes to your body and lead to internalexposure.

2.) Refrain from these activities in all radioactive materialwork areas and avoid touching your eyes, nose, and lips.

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Case 16

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Case 16

• What is the hazard or compliance issue in this picture?

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Case 16

• Answer: This staff member is standing in the highestradiation scatter zone!

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Case 16

• Scatter profile for CT scanners is forward along the table.

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Case 16

• The side of the CT scanner has lower scatter and is apreferable place to stand than next to the table.

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Case 16

Key Concepts:

1.) The CT scanner tend to throw radiation forward andbackward along the length of the patient bed.

2.) If possible, it’s better for staff and family member tosneak around to the side of the scanner during theacquisition to reduce their own exposure.

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Case 17

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Case 17

• What is the hazard or compliance issue in this picture?

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Case 17• Answer: Staff member is using frontal apron but has back

turned to source of radiation!

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Frontal “Drop” Lead Apron Type

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Skirt Vest Type Apron

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Case 17

Key Concepts:

1.) Be careful if you are wearing a front apron that you arefacing the source of radiation and do not get your bodyrotated.

2.) Wear a skirt/vest style apron in circumstances when youcannot always face the procedure (ie. if you are circulating).

3.) If you have no other option, wear two front lead aprons,one front-ward, the other back-ward to protect your organsfrom all sides.

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Acknowledgements

Jackie ChoragwickiMerima KarastanovicJudy Le

THANK YOU!

Christina L. Sammet, Ph.D., DABRMedical PhysicistRadiation and Laser Safety Officer

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